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A hyperpolarization-activated cation current (I h) contributes to resting membrane potential in rat superior cervical sympathetic neurones

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Abstract

 Using perforated-patch voltage-clamp recording, a prominent hyperpolarization-activated inward cation current (I h) has been identified in dissociated, cultured and replated, superior cervical sympathetic (SCG) neurones from 17-day-old rats. I h was identified as a slowly activated inward current on hyperpolarizing from –60 mV, with an extrapolated null potential (in 3 mM [K+]out) of –42 mV. The activation range for I h was –40 to –100 mV, with a half-activation voltage (V 0.5) of –63 mV. The current was suppressed by 1 mM Cs+ but not by 1 mM Ba2+. The reversal potential for the current change induced by Cs+ agreed with the null potential for I h. I h conferred strong inward rectification to the current-voltage curve negative to –55 mV in both voltage-clamp and current-clamp recording. This inward rectification was reduced by 1 mM Cs+. In a sample of eight cells with initial resting membrane potentials between –51 and –64 mV, Cs+ increased the resting potential of all cells by between 2.5 and 21 mV. These results indicate that I h contributes a tonic inward (depolarizing) component to the maintenance of the resting membrane potential in SCG neurones.

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Received: 16 January 1998 / Received after revision and accepted: 1 April 1998

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Lamas, J. A hyperpolarization-activated cation current (I h) contributes to resting membrane potential in rat superior cervical sympathetic neurones. Pflügers Arch 436, 429–435 (1998). https://doi.org/10.1007/s004240050653

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  • DOI: https://doi.org/10.1007/s004240050653

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